1. Field of the Invention
The present invention relates to a carbon heater incorporating a carbon fiber or a carbon filament, which is used as a heating element, and, more particularly, to a carbon heater having support parts, which are integrally formed at the carbon filament while being protruded from the carbon filament such that the support parts are supported inside a quartz tube.
2. Description of the Related Art
Generally, a carbon heater is a heater that uses a filament made of carbon as a heating element. As it became known that the carbon heater has excellent thermal efficiency, does not harm the environment when the carbon is discarded, and provides several effects, such as far infrared radiation, deodorization, sterilization, and antibacterial activity, the carbon heater has been increasingly used in room-heating apparatuses and drying apparatuses as well as heating apparatuses.
FIG. 1 is a perspective view schematically illustrating a conventional helical carbon heater, and FIG. 2 is a longitudinal sectional view of principal components of the conventional helical carbon heater illustrated in FIG. 1.
As shown in FIGS. 1 and 2, the conventional carbon heater comprises: a quartz tube 10 whose interior is hermetically sealed by tube sealing parts 11 disposed at both ends of the quartz tube 10; a helical carbon filament 12 arranged longitudinally in the quartz tube 10; metal wires 14 attached to both ends of the carbon filament 12 while extending to both ends of the quartz tube 10, respectively; and external electrodes 16 electrically connected to the metal wires 14 via metal pieces 18 disposed in the tube sealing parts 11 of the quartz tube 10, respectively, while being exposed to the outside of the quartz tube 10.
The interior of the quartz tube 10 is hermetically sealed, and the interior of the quartz tube 10 is maintained in vacuum or filled with an inert gas such that the carbon filament is not oxidized at a temperature of 250 to 300° C.
The carbon filament 12 is formed in a helical shape, and the metal wires 14 are connected to both ends of the carbon filament 12, respectively.
FIG. 3 is a longitudinal sectional view illustrating principal components of another conventional carbon heater incorporating a sheet-shaped carbon filament.
As shown in FIG. 3, the conventional carbon heater comprises: a sheet-shaped carbon filament 22 disposed in a quartz tube 20; carbon rods 24, for example, cylindrical graphite bars, in which both ends of the sheet-shaped carbon filament 22 are fitted, respectively; and springs 25 connected between the carbon rods 24 and metal wires 23, respectively, for providing tension forces to the carbon filament 22.
In FIG. 3, reference numeral 26 indicates external electrodes, and reference numeral 28 indicates metal pieces connected between the external electrodes 26 and the metal wires 23, respectively.
The carbon filament is formed in a helical shape as shown in FIG. 2, or the carbon filament is formed in the shape of a sheet as shown in FIG. 3, although the carbon filament may be formed in any other shape. For example, the carbon filament may be formed in the shape of a straight line, a fabric, or a sponge.
For the helical carbon filament 12 as shown in FIG. 2, both ends of the helical carbon filament 12 are tied to the metal wires 14, respectively, such that contact resistance is reduced at the connections between both ends of the helical carbon filament and the metal wires 14. For the sheet-shaped carbon filament 22 as shown in FIG. 3, both ends of the sheet-shaped carbon filament 22 cannot be tied to the metal wires 23, respectively. For this reason, a slit is formed at each carbon rod 24 such that both ends of the sheet-shaped carbon filament 22 are fitted in the slits of the carbon rods 24, respectively. Also, the springs 25 disposed at outer ends of the carbon rods 24 apply tension forces to the carbon rods 24, and thus, the carbon filament 22.
In the carbon heater as shown in FIG. 3, however, both ends of the sheet-shaped carbon filament 22 are securely fitted in the carbon rods 24, respectively, and then the carbon rods 24 are connected to the metal wires 23 by the springs 25, respectively. As a result, the carbon filament connection structure is complicated, and therefore, the whole structure of the carbon heater is complicated. Consequently, the manufacturing costs of the carbon heater are considerably increased.
Especially in the conventional carbon heater as described above, the carbon filament 22 is tensioned by the carbon rods 24, the springs 25 and the metal wires 23 disposed at both ends of the carbon filament 22, respectively, such that the carbon filament 22 is supported in the quartz tube 20. As a result, the carbon filament 22 is lengthened after the conventional carbon heater is used for a long period of time, and therefore, the carbon filament 22 comes into contact with the inside of the quartz tube 20.